Tuesday, August 18, 2009

stem cells Buried under all the uproar over proposed healthcare reform legislation, there has been some significant news this summer regarding stem cell research. To begin, let’s recall some of the basics of this issue.

What are stem cells?

Maureen Condic, Senior Fellow with the Westchester Institute, concisely responds to that question in a recent article in Ethics and Medics:

A stem cell is any cell that exists in a relatively immature state, and is able to divide to produce one cell that replaces itself and one that will go on to become a more specialized cell type. Because stem cells replace themselves every time they divide, they are considered self-renewing, or “immortal.”

There are three broad classes of stem cells: embryonic, adult, and reprogrammed. Human embryonic stem cells are obtained by the destruction of human embryos that are between three and six days old. At this early stage, cells of the embryo are still very primitive and are pluripotent; i.e., they are able to produce all of the cell types found in the mature human body.

In contrast, any stem cell that is found in a specific type of tissue (whether in an older embryo, a fetus, or a more mature individual) is considered an adult stem cell. Adult stem cells are thought to be more limited, making only the types of cells appropriate to the tissue in which they reside. Thus, they are seen as merely “multipotent.”

Finally, recent studies have shown that adult body, or “somatic,” cells can be reprogrammed to a state very similar to a human embryonic stem cell. These induced pluripotent stem cells, or iPSCs, are not identical to embryonic stem cells, but they are functional equivalents.

Why is stem cell research important?

It is hoped that stem cell research will unearth scientific clues that will one day lead to remarkable breakthroughs in dealing with diseases treatable by tissue replacement therapies.

Does the Catholic Church oppose stem cell research?

The Catholic Church has enthusiastically supported the better part of stem cell research, especially adult stem cell research and new techniques such as cell reprogramming. We cannot, however, support research which involves the creation and destruction of human embryos.

What is happening with adult stem cell research?

Scientists in this specialized area of stem cell research continue to be fully engaged in their work and well funded, even though adult stem cell research gets much less media attention. Do No Harm, the Coalition of Americans for Research Ethics keeps a running tally on reported applications of adult stem cells that produce therapeutic benefit for human patients. Experts are currently at work on updating that list, but estimate that approximately 80 different diseases have now been shown to be treatable in some degree by adult stem cells.

Are scientists still trying to clone human embryos?

Some scientists continue to be irreversibly committed to using cloning techniques to create human embryos which, after about six days of development, would then be destroyed to cull embryonic stem cells from them. These stem cells would be genetically matched to the donor who was the source of the cloning; tissues derived from the cloned cells could then potentially be used to treat the donor.

This prospect, of course, has proven to be easier said than done. To date, only three research teams are known to have successfully cloned human embryos, but no team was able to derive stem cells from the clones. Technical hurdles remain which make human cloning extremely difficult, inefficient, and expensive. One lingering hurdle is the dearth of available human eggs for such experiments. Given the paucity of women willing to undergo the dangerous procedure of ovarian stimulation for the retrieval of their eggs, at least one British team of researchers attempted a repulsive variation of human cloning using bovine eggs, the resulting product of which has been termed a ‘cybrid’.

Next week, in part II of this column on stem cell news, I’ll explain how the dearth of available human eggs for stem cell research has led to a cash-for-eggs scheme in New York, and I’ll discuss recent breakthroughs in ethically acceptable areas of research.***